Protection of resistors of electric furnaces



May 1, 1923. v 1,453,397

" G. M. LITTLE PROTECTION OF RESISTORS 0F ELECTRIC FURNACES Filed April 21, 1921 WITNESSES: I I INVENTOR I George M, Liffle ATTORNEY Patented May 1, 1923.

UNITED. STATE PATENT UFFHCE.

GEORGE-HI. LITTLE, OF PITTSBURGH, PEET"SYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING Ci'ksIPi-LNYZ', A CORPORATION OF E'ENNSYLVANLL l, 1 1- Application nied April 21, i921. Serial No. 463,220.

To aZZ whom it may concern Be it known that l, Gnoiion hi. Lrr'rLn, a

citizen of the United States, and a resident of Pittsburgh, in ti o county of Lille and State of Pennsylvania, have ii a new and useful linprovement in krotection of llesistors of Electric Furnaces, of which the fol owing is a speci-"ication.

lily invention relates to eleclricacsistancc furnaces and particularly to carbonaceous resistors for such furnaces and it has for its object to provide means for protc ing such carbonaceous resistors against the of ingeffect of air entering the furnace her.

As is Well known in the electric furnace art, carbonaceous resistor elementr-z, when operated at relatively high temperature in the open air, are rapidi oxidi vhens-by and,v

sistor elements has sometimes bee" afforded by providing them with envelopes of some non-oxidising material, such as carborumlum or silicon carbid. Since the resistor elements are thus made relatively bulky and hard to repair quicizly, it is desirable that a more simple protective means be employed.

in practicing my invention, 1 provide a lamp burning an inflammable oil and permit the flame to burn with an insu'iiicient supply of air, thus causing a smoky flame and the generation of sooty vapors. These vapors are permitted to enter the furnace chamber and to impinge upon the carbo" naceous resistor and be deposited thereon. Some of the sooty vapors will strike the Walls of the furnace chamber and be deposited thereon.

The single figure of the drawing;- is a view, in vertical cross section, of an electric furnace comprising the device embodying my invention.

An electric furnace 10 comprises an outer metallic frame WOl'k 11 provioeo with suitable supports 12. An outer lining;' coo:-

her

A resistor 16 comprises a plurality of carbonaceous elements, this resistor being sub stantially of the type described in a copending application, Serial No. 154,77 6, filed by me, lilarch 2 3, 1921, and. assigned to the l'l estinghouse Electric and Maine lecturing Uompany.

An opening 17 is provided at the front of the furnace substantially at the bottom of the chamber 15 to permit of introducing me l'allic articles into the chamber to be heated by the resistor.

it the back of the furnace, is provided a suitable opening 18 through the wall in which is removably located a tube 19. At the outer end of the tube 19 is located a depending elbow member 20, both the members l9 and 20 being of relatively large diameter and being easily and quickly removable from their operative positions.

A lamp 21 is mounted on a suitable supporting member 22, carried by the supports l2. The lamp 21 may be of any siiitable size and shape to hold a supply of inflammable oil. A member 23, here indicated as of inverted saucer-shape, is adjustably mounted on the lamp 21 to permit of regulating the supply of air to the flame of the lamp. It may be noted that, by so rotating the member on the cooperating threaded stem 2% as to move it upwardly, less air is permitted to e ch the flame of the lamp, thus causing greater amount of sooty vapor.

he sooty vapor generated by the lamp en ers the elbow member and flows into ie furnace chamber 15 through the tube 19. y reason of the tendency of the incoming ii ises t flow toward the upper part of the chamber the sooty vapor is carried upuardly and strikes the resistor element as well as the inner surface of the lining l4 and the soot is deposited thereon. The deposited soot protects the elements of the resistor 16 against the oxidizing effect of air Which may leal: through the opening; 17 or past the outside of the tube .19 in the opening 18, the oxidizing effect of the air being expended upon the sooty covering instead of on the resistor elements. By continuously providing a suflieic-nt amount of sooty vapor, the resistor 16 may be protected completely against the oxidizing effect of the air. t

In case the elbow 20 and the tube ll) become clogged by deposits of soot, they may ill) be easily and quickly removed, disassembled, cleaned, and then replaced Without interfering with the continuous operation of the furnace itself.

It may be noted that the device embodying my invention provides relatively simple means for causing a sooty vapor to be continuously deposited upon the surface of a carbonaceous resistor to protect the same against oxidization.

Various modifications may be made in the device embodying my invention without departing from the spirit and scope thereof and I desire that only such limitations shall be placed thereon as are imposed by the prior art or are specifically set l'orth in the appended claim.

I claim as my invention:

In an electric furnace, the combination with a housing enclosing a furnace chamber and having an opening near the bottom of said chamber for introducing material to be heated, and a carbonaceous resistor located near the top of said chamber, of a' source of hydrocarbon vapor comprising an oil flame, means for conducting the products of combustion of said flame into said chamber near the bottom thereof and means for varying the amount. of hydrocarbon vapor produced by said flame.

In testimony whereof, I have hereunto subscribed my name this 11th day of April, 1921.

GEORGE M. Ll 'lTLE. 

